CONTENT AND SYNTHESIS OF HEPATIC PYRIDINE NUCLEOTIDES IN FETAL AND NEONATAL RABBITS.

Abstract

The concentration and the synthesis of pyridine nucleotides in the liver and placenta of the rabbit have been studied as a function of developmental age. The concentration of total hepatic pyridine nucleotides increased progressively during fetal and neonatal development, reaching a maximal level in the adult period. This increase was due primarily to elevation in diphosphopyridine nucleotide (DPN) and reduced triphosphopyridine nucleotide (TPNH). In the postmature state, hepatic reduced diphosphopyridine nucleotide (DPNH) and triphosphopyridine nucleotide (TPN) levels were less than in term or 5-day-old rabbits. The concentration of total pyridine nucleotides in the placenta diminished during gestation. Following parenteral administration of nicotinamide to the pregnant rabbit, the concentration of nicotinamide increased to the same extent in maternal and fetal blood plasma and the total pyridine nucleotide concentration increased in both maternal and fetal liver. The latter increment was greater in maternal than in fetal liver, and in fetal liver was greatest at term. The increase was due largely to increase in DPN in the developing fetus and neonate, and in the adult rabbit to increase in all pyridine nucleotides.